Instead of conducting an evaluation test by driving a (assembly-)finished vehicle on a road, recently, a drive wheel(s) of the finished vehicle is placed on a roller of chassis dynamometer for evaluation. In such a case, a running-resistance load which is generated by the road running of the vehicle is simulated by setting an absorption load torque of the chassis dynamometer. At this case, a running resistance has been obtained by causing the vehicle to coast on an actual road such as a test course in advance. When such a running-resistance data is obtained, the environment such as wind velocity, air temperature, air pressure and humidity takes a wide range of variations. Hence, the obtained data is treated as a data under a standard atmospheric condition (air temperature: 20° C., air pressure: 101.3 kPa, calm wind), in order to determine a target running resistance.
However, the running resistance obtained on the actual road is influenced by its environment, particularly by air pressure. For example, since air density is low at a high altitude of 3000 m above sea level, a percent for which an air resistance accounts in the running resistance is low so that a vehicle running is influenced and different at a highland. Therefore, as an environmental test device designed for a vehicle which runs at a high altitude, Patent Literature 1 is know. This Patent Literature 1 discloses that air pressure of a low-pressure environmental test laboratory is controlled by using a suction blower or a pressure-reducing blower.
Patent Literature 1: Japanese Patent No. 4-068578